The present invention relates to osteosynthesis means for the treatment of bone fractures and in particular for the connection of bone fracture segments.
The assemblies currently employed for the treatment of bone fractures substantially comprise a plate secured surgically to one of the bone fracture segments, e.g. by means of one or more screws inserted through holes on the plate and screwed into matching holes on the bone segment; and at least one screw inserted through a further hole on the plate and screwed into a matching hole on both segments. Once the bone segments are firmly knit, the various elements in the assembly are removed. Said second screws inserted inside the second segment for connecting it to the first are longer than those connecting the plate to the first segment, and must be positioned at a predetermined angle in relation to the plate, so as to fit precisely inside the matching holes on the second segment.
Assemblies of the type briefly described above present a number of drawbacks.
Firstly, they fail to provide for correct support between the plate and mating segment when the screws connecting the two segments are screwed inside the respective holes on the same. This is due to the axes of said screws forming a predetermined angle in relation to the plate, which permits no or only a very small amount of adjustment, i.e. that permitted by the slack between the hole in the plate and the screw shank. Very rarely, however, does said angle correspond to that formed between the axes of the holes in the bone segments and the plate supporting surface on the bone.
Secondly, assembly of the various component parts involved to the bone segments is not only difficult but requires considerable care and skill.
Thirdly, the versatility of assemblies of the aforementioned type is extremely limited, by virtue of the size and shape of the component parts depending on the geometrical characteristics of the bone segments for connection.
Fourthly, known assemblies of the aforementioned type may lead to complications and delayed healing of the fracture in the period immediately following the surgical operation. During this period, in fact, absorption generally takes place at the fracture surfaces, thus altering the position of the ends of the bone segments, which, using known assemblies of the aforementioned type, are prevented from moving by the rigid restraints consisting of the plate and respective screws. This results in undue stress on the fracture surfaces, which may even be caused to move away from each other.
Finally, the mechanical strength and stability of the connection provided for by such assemblies are fairly poor, so that steps must be taken for preventing relative movement of the bone segments in the period immediately following surgery.